RFR(S): ZGC: C2: Oop instance cloning causing skipped compiles

[Nils Eliasson]

I updated this to version 2.

http://cr.openjdk.java.net/~neliasso/8234520/webrev.02/

I found a problen running compiler/arguments/TestStressReflectiveCode.java

Even though the clone was created as a oop clone, the type node type 
returns isa_aryprt. This is caused by the src ptr not being the base 
pointer. Until I fix that I wanted a more robust test.

In this webrev I split up the is_clonebasic into is_clone_oop and 
is_clone_array. (is_clone_oop_array is already there). Having a complete 
set with the three clone types allows for a robust test and easy 
verification. (The three variants end up in different paths with 
different GCs).

Regards,

Nils


On 2019-11-20 15:25, Nils Eliasson wrote:
> Hi,
>
> I found a few bugs after the enabling of the clone intrinsic in ZGC.
>
> 1) The arraycopy clone_basic has the parameters adjusted to work as a 
> memcopy. For an oop the src is pointing inside the oop to where we 
> want to start copying. But when we want to do a runtime call to clone 
> - the parameters are supposed to be the actual src oop and dst oop, 
> and the size should be the instance size.
>
> For now I have made a workaround. What should be done later is using 
> the offset in the arraycopy node to encode where the payload is, so 
> that the base pointers are always correct. But that would require 
> changes to the BarrierSet classes of all GCs. So I leave that for next 
> release.
>
> 2) The size parameter of the TypeFunc for the runtime call has the 
> wrong type. It was originally Long but missed the upper Half, it was 
> fixed to INT (JDK-8233834), but that is wrong and causes the compiles 
> to be skipped. We didn't notice that since they failed silently. That 
> is also why we didn't notice problem #1 too.
>
> https://bugs.openjdk.java.net/browse/JDK-8234520
>
> http://cr.openjdk.java.net/~neliasso/8234520/webrev.01/
>
> Please review!
>
> Nils
>